[-next,v2] dmaengine: mcf-edma: fix x86_64 allmodconfig compilation warning

[Angelo Dureghello <angelo@sysam.it>]

Hi Geert,

On Fri, Sep 14, 2018 at 01:35:22PM +0200, Geert Uytterhoeven wrote:
> Hi Angelo,
> 
> Thanks for your patch!
> 
> On Fri, Sep 14, 2018 at 9:12 AM Angelo Dureghello <angelo@sysam.it> wrote:
> > This patch fixes the compilation warning reported
> > during x86_64 allmodconfig build.
> 
> Please quote the warning, so people know what it is about:
> 
>     drivers/dma/mcf-edma.c: In function 'mcf_edma_filter_fn':
>     drivers/dma/mcf-edma.c:296:33: warning: cast from pointer to
> integer of different size [-Wpointer-to-int-cast]
>        return (mcf_chan->slave_id == (u32)param);
> 

Ok done.

> > Reported-By: Stephen Rothwell <sfr@canb.auug.org.au>
> > Signed-off-by: Angelo Dureghello <angelo@sysam.it>
> > ---
> > Changes for v2:
> >   - added Reported-By
> > ---
> >  drivers/dma/mcf-edma.c                     | 3 ++-
> >  include/linux/platform_data/dma-mcf-edma.h | 2 +-
> >  2 files changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/dma/mcf-edma.c b/drivers/dma/mcf-edma.c
> > index 4d30d5302649..e08e2409a102 100644
> > --- a/drivers/dma/mcf-edma.c
> > +++ b/drivers/dma/mcf-edma.c
> > @@ -292,8 +292,9 @@ bool mcf_edma_filter_fn(struct dma_chan *chan, void *param)
> >  {
> >         if (chan->device->dev->driver == &mcf_edma_driver.driver) {
> >                 struct fsl_edma_chan *mcf_chan = to_fsl_edma_chan(chan);
> > +               unsigned int req = *(unsigned int *)param;
> 
> This looks a bit hackish to me.
> >
> > -               return (mcf_chan->slave_id == (u32)param);
> 
> The recommended way to cast from pointers to integers is to
> use uintptr_t, which always has the same size as a pointer, i.e.:
> 

slave_id is acually an u32. So, if i understsand, when compiled
on x86_64 using uintptr_t, the cast should trigger the same issue. 
I preferred, as i.e. ti/omap dma driver is doing, to simply 
use a pointer to an int (int[]) as passed type in param,
so i can then indirectly access the integer. I tested
proper functionality in ColdFire and that there are no warnings
anymore in both ColdFire and x86_64 allmodconfig so the patch,
hopefully, should be legal.  

>         return (mcf_chan->slave_id == (uintptr_t)param);
> 
> > +               return (mcf_chan->slave_id == req);
> >         }
> >
> >         return false;
> > diff --git a/include/linux/platform_data/dma-mcf-edma.h b/include/linux/platform_data/dma-mcf-edma.h
> > index d718ccfa3421..97cb79bda646 100644
> > --- a/include/linux/platform_data/dma-mcf-edma.h
> > +++ b/include/linux/platform_data/dma-mcf-edma.h
> > @@ -21,7 +21,7 @@ struct dma_slave_map;
> >
> >  bool mcf_edma_filter_fn(struct dma_chan *chan, void *param);
> >
> > -#define MCF_EDMA_FILTER_PARAM(ch)      ((void *)ch)
> > +#define MCF_EDMA_FILTER_PARAM(ch)      ((int[]) { (ch) })
> >
> >  /**
> >   * struct mcf_edma_platform_data - platform specific data for eDMA engine
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
Regards,
Angelo

> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds